A semiconductor integrated circuit, which may include a memory device, is provided with an internal supply voltage generator to provide an optimum voltage lower than an external voltage. Such an internal supply an voltage is applied to various internal circuits to drive them.
A conventional internal supply voltage generation circuit is described in Japanese Patent Laying Open Kokai No. H5-205469. In the conventional internal supply voltage generation circuit, a reference voltage and an external supply voltage are selectively used to generate an internal supply voltage.
In general, device characteristics including supply current and access time vary in response to the level of such an internal supply voltage. The internal supply voltage varies in response to an external supply voltage, temperature, process parameters, and the like. For providing an optimum internal supply voltage, a reference voltage and/or the internal supply voltage are corrected in level with a trimming circuit.
According to the above mentioned conventional circuit, it is difficult to obtain an optimum internal supply voltage without expanding an area of the trimming circuit in the semiconductor integrated circuit. This means that it is required to increase the number of fuses and other electrical components to be mounted in the trimming circuit for expanding the rage of level correction (trimming) and narrowing the interval of each correction level. When the area of the trimming circuit is expanded, the area of the semiconductor integrated circuit is eventually expanded as well.